ML24346A178

LLC - Response to SDAA Audit Question Number A-4.3-33

ML24346A178
Person / Time
Site:	05200050
Issue date:	12/11/2024
From:	NuScale
To:	Office of Nuclear Reactor Regulation
Shared Package
ML24346A130	List: ML24346A131 ML24346A132 ML24346A147 ML24346A165 ML24346A167 ML24346A169 ML24346A173 ML24346A174 ML24346A175 ML24346A176 ML24346A177 ML24346A178 ML24346A181 ML24346A185 ML24346A187 ML24346A193 ML24346A195 ML24346A197 ML24346A245 ML24346A247 ML24346A257 ML24346A258 ML24346A260 ML24346A262 ML24346A264 ML24346A270 ML24346A272 ML24346A273 ML24346A274 ML24346A276 ML24346A277 ML24346A280 ML24346A282 ML24346A283 ML24346A284 ML24346A286 ML24346A287 ML24346A289 ML24346A294 ML24346A295 ML24346A297 ML24346A299 ML24346A300 ML24346A302 ML24346A303 ML24346A306 ML24346A308 ML24346A310 ML24346A312 ML24346A314 ... further results
References
LO-175762
Download: ML24346A178 (1)

Text

Response to SDAA Audit Question Question Number: A-4.3-33 Receipt Date: 06/24/2024 Question:

Shutdown margin calculations presented in FSAR Table 4.3-3 apply an uncertainty factor of 12% to the difference between the CRA worth and the power defect, where CRA worth accounts for positioning of CRAs at PDILs and the worst rod stuck out, as described in Section 5.3 of EC-A021-3589. (( 2(a),(c) However, CRA worth and power defect are different phenomena, and applying CRA worth uncertainty to the difference between CRA worth and power defect may artificially reduce CRA worth uncertainty in the shutdown margin calculation. (( }} 2(a),(c) Provide revised SDM calculations with CRA worth NRFs applied to CRA worth.

Response

The method for calculating shutdown margin presented in FSAR Table 4.3-3 is revised to apply the control rod worth uncertainty ((

}}2(a),(c) similar to how it was applied in the US600 application.

Markups of the affected changes, as described in the response, are provided below: NuScale Nonproprietary NuScale Nonproprietary

NuScale Final Safety Analysis Report Nuclear Design NuScale US460 SDAA 4.3-24 Draft Revision 2 Audit Question A-4.3-29, Audit Question A-4.3-33, Audit Question A-XPC.LTR-14 Table 4.3-3: Reactivity Requirements for Control Rods BOC MOC EOC Control Rod Assembly Worth (pcm) Total available CRA worth (a) 1495414920 1638116305 1706416946 Power dependent insertion limits (b) 510524 642666 769797 Worst rod stuck out (c) 63026223 58765802 67686679 Subtotal (a-b-c=d) 81428173 98639837 95279470 Reactivity Allowances and Uncertainties (pcm) Power defect (e) 30553104 39023967 59486036 Uncertainty (g) 977608 1184704 1143412 Shutdown Margin Available (d-e-g) (pcm) 41104461 47775166 24363022

NuScale Final Safety Analysis Report Nuclear Design NuScale US460 SDAA 4.3-43 Draft Revision 2 Audit Question A-4.3-29, Audit Question A-4.3-33, Audit Question A-XPC.LTR-14 Figure 4.3-16: Maximum and Minimum Power Defect}}